Means for preventing electrical interference



Nov. 10 1925- s. I. CORY MEANS FOR PREVENTING ELECTRICAL INTERFERENCE Filed Feb. 1, 1922 i a I ulll INVENTOR ATTORNEY Patented Nov. 10, 192.

um'r En STA -T Es 1,560,540 PATENT OFFICE;

SAMUELI. conY, or nmvrnnnsm nnw YORK, Assienon mojnivrnnicimmntntiionn AND TELEGRAPH'GOMPANY, A CORPORATION OF NEW YORK.

Application filed Febinaiy -To all whom 11mg] (o 126 2 72 Be it known that I, SAMUEL I. Conig residing atElln hurst, in the county" of Queens and State of New Yoi'lggli'aye invented cer- 5 ta in linprovenientsin Means for Preventing Electrical Interference, of which the following is a specification.

'lhisinvention relates to neansfor preventing electrical interference between signeling circuits, alidfespeci'ally to an arrangement for preventing thzit foi'in oi't" interference between grounded telegraph circuits which is terinecl receiving'encl"cross iirei' In" the operzition" o'l grounded telegraph circuits it is well known that when signaling i puls s are tra-nsi 'itted over one telegraph circuit, an interfering curi'en't will he set up in other circuits 1mi'allelingthe first" circuit due to the n'nit uals dinitt tnce between the circuit oyeir which th'e impulses are being transmitted, here sen-er referred tons the disturbing:circuit; 'an'dthcjcircuit or circuits paralleling the said circuit, hereinafter referred to as v the disturbed circuit or circuits." This interfering"current will cause a clisturbzi-nce in the termin'ei apparetusf at both ends of the disturbed circuit or circuits. l hedisturb2incewhich is setup in the terminal apparatus of e' clistui'heclcircuitldcgitcl' in the sainestation in wh ich'is alsolocetedthe terminal eppa ratus from which the signaling iinpi'ilses are being inipressed upon the said disturbing circuit, may be termed sei'irling-end jcross lirc. The disturhnnce whichis set up in the terminal ap'pmee r the disturbed circuitloc'at'ed in the? same stetion' in which is "also located there'ceiving'" apparatus of the said distuih ingcircuit; may be termed receiiing-end' 40 cross-j'fire'." s e'nding en 'd cross-fire in, distri'rbed' circuits has been" successfully nentrelized by connecting a condenser (preferably finseries' with a, resistance)=hetween tneertificial lines of the duplex sets of the disturbing and the disturbed circuits.

It I is'the object of this invention toiprovideja circuit arrangement for substantially disturbed circuits without increasing the 0 sending encl cross-fire such as has resulted from the use of arrangements heretofore clesigne'd for'this pnrpesei Othfr' and vfurtherobjects of ithisinventionfwillzbe apparent from the following, de

scription; when reed in connection with the 1, 152%. Serial NS. 533,370.

attached drawing showing one form of chibodiment of thc invention.

In the drawing; 1 and 2 represent two telegraph signiiling' circuits which hei e essocinted therewith the terminal circuits A and C respectively at station and B and The tern'iin-lil circuitat A coinprises a pole changer 7, the operation of which is controlled by the apparatus connected with the loopcircuitfl represented by the key lOiand the battery 9 The errnature 13 of the pole changer is adapted to nioi e between two 'cont ects, of which the left-hand one is connected with the negsitiye battery 11, and

the right-hand one with thepositive battery "12. The armature 13 is connected with the apex of the bridge coi1sQ3, the connection including serially. the primary winding le of a transforineriw, which is shuntedby'e veriablejresistan'ce 1G by means or" which the 'lniignitnde of the current flowing through thesnid winding niey be controlled.

TheQterniinel circuit C: 'con nec'ted ivith 'lhe" lin'e circuit 2 issimilantothe terininel circuit A., It includes a. pole changer 19 connected with a loop circuit 20, ha'ving n key 21 and a, battery 22 associated-therewith} arindtnre' of the polie chz njger 1s adepted to moye between two; contacts, of

I which theleft-hand one is. connected with the negative, battery 24, end the right-handonc the positiife battery This arn'izitureisiconnected with the ape ei thefcoils h 18, the connection including serially ,n neutralizing the TGCGlVifig G-Dfil cross-fire 1n secondary winding26 of the transformer '15, which is shunted bya variable resistance 27. The artificial line side of the bridge coilsfi isconnected with the corresplonclingi'side of the coilsl l8bye condenser 17 pre i er'ably in serieswi'th arresiistinice28, theiconnection 'ser vin'gto eliminate sending end' cross-fire.

Cal

I or circuits.

The terminal circuits B and at the station Y are similar to the circuits A and C and need no further description in orderthat they may be clearly understood.

Having in mind the foregoing descrip tion of the apparatus connected with the circuits in which this invention is embodied, the invention will be clearly understood from the following description of the mode of operation of the invention.

Let it be assumed that signals are being transmitted from the terminal circuit A to the distant terminal circuit B over the line 1, so that, in respect to interference, the said line becomes the disturbing circuit of the system, and line 2 and other lines similarly situated become the disturbed circuit lVhen the key 10 is closed, as in the figure, current from the battery 9 flowing through the loop 8 will energize the pole changer 7, so that the armature 13 touches its lett-hand contact, so that. a negative impulse from the battery 11 is trans mitted over the connection between the armature and the apex of the bridge coils 3. This negative impulse will cause current to How over the line 1 from the distant end in the direction represented by the arrows shown by light solid lines, and will operate the receiving relay 6 connected across the bridge coils 4. The transmission of this current over the line 1 will set up in line 2, and other lines similarly situated, an in rection of which will cause a neutralizing current to flow in the line 2 in the direction shown by the heavy solid arrows which will substantially neutralize the interfering current in the distant relay 30.

The neutralizing current and the inter fering current will be transmitted over the line 2, and, if of approximately the same wave shape and in proper phase, they will substantially balance each other, thereby minimizing the effect of cross-fire upon the apparatus at the receiving end of the circuit. The magnitude of the neutralizing current may be controlled by the proper adjustment of the Self and mutual inductance of transformer 15 or the variable shunt resistances 16 and 27. Since this neutralizing current is applied to the apex of the coils 18, it will have no detrimental effect upon the relay 29 at the transmitting end of line By means of the condenser 17 in series with resistance- 28, the effect of the interfering current upon relay 29' is substantially neutralized. Current flowing in the artificial line branch of the bridge coils 3, as the result of the impression of the signaling impullse upon the apex of the said coils 3 will cause a neutralizing current to flow in the artificial line branch of bridge coils 18, by way of the condenser 17 and resistance 28.

It will, of course, be understood that when an impulse of opposite polarity is applied to the line 1 by the battery 12, the interference currents in line 2, represented by the dotted arrows, will be in the opposite directions, as will also be the neutralizing current represented by the heavy solid arrows. In a similar manner, when the key 21 of the loop circuit of the terminal circuit 0 is closed, a negative impulse from the battery 24 will flow over the connection be tween the armature 23 and the apex of the bridge coils 18. This current will flow through the winding 26, which will induce a difference of potential across the winding 14, which is connected with the line 1. The transmission of the current over the line 2 will not only operate the receiving apparatus connected with the distant end of the said line, but, by virtue of the said mutual admittance between the line 2 and the line 1 and other lines similarly situated, will set up an interfering current inthe said line 1 and the other lines. This interfering current set up in line 1 will be substantially neutralized in relay 6 by the neutralizing current resulting from the difi'erence of potential induced across the terminals of the winding let by the current flowing through the winding 26, which induced potential is adapted to produce a current of correct size, shape and phase to neutralize the interfering current existing in the relay 6 due to the transmission of the signaling impulse over the line 2. As stated hero toitore, the impression of the neutralizing current upon the coils 3 produces no detrimental etlect upon the receivingrelay 5, in view of the difi'crentiai connection of the coils. By means of the condenser 17 and resistance 28, the eiiect of the interfering current upon relay 5 is substantially neutralized by the current flowing in the artificial line branch of the bridge coils 18, as the result of impressing the signaling current upon the apex of the said coils.

Although the transformer '15 is represented as having only two windings, which are connected with the two line circuits shown in the drawing, it is to be understood neeowc'o naling impulse over any line-circuit connected witlr the said transformer winding will induce neutralizing impulses in the other windings of the said transformer in such direction as to neutralize the; interferingcurrents set-up in the other line circuits of thesaid system connected with the said other transformer windings in which the neutralizing impulses are generated.

It will be seen from the foregoing description that my invention discloses simple and effective n'ieans for protecting parallel telegraph circuits against receiving-end interference. Although this invention has been described as embodied in a particular form and arrangement of parts, it is to be understood that it is capable of embodiment"- in other forms and arrangements without de parting from the spirit and-scope of the ap pended claims.

\Vhat is claimed is:

1. In a system for reducing rcccimng-cnd cross-lire in telegraph circuits, the method which consists in transmitting over any circuit of a system a signaling impulse adapted, by the admittance of the system, to create an interfering impulse in the other circuits of the system, and simultaneouslyinducing in the other circuits of the systenu-by means of the transn'iission of the said signaling impulse overthe said first'meni ioned circuit, neutralizing impulses to substai'itiall neutralize the effect. of the interfering impulse upon the distant receiving apparatus of the said other circuits.

2. In a system for reducing receiving-end cross-fire in telegraph circuits, the method which consists in transmitting over a circuit of a system a signaling impulse adapted, by the admittance of the system, to create an interfering impulse in the other circuits of the system, and impressing upon the said other circuits a neutralizing impulse without affecting the receiving apparatus at the point of application, but adapted to non tralize the effect of the interfering impulse upon the receiving apparatus more remote from the point of application of the said neutralizing impulse, the said neutralizing impulse being created inductively by the signaling impulse in said first circuit.

3. In a system for reducing receiving-end cross-fire in telegraph circuits, the method which consists in transmitting over a circuit of a system a signaling impulse adapted. by the admittance of the system, to create an interfering impulse in the other circuits of the system, and impressing upon the said other circuits a neutralizing impulse without affecting the receiving apparatus of the said other circuits at the point of application but serving to neutralize the effect of the interfering nnpulse upon the distant apparatus of the said other circuits.

l. In a system for reducing receiving-end cross-tire in telegraph circuits, the method which consists in. impressing upon any, cir-.- cuit ofa system signalingncurrents tendi to produce in the other circuits, of the admittance of the. system,. currents having at the. distant ends oi other circuits the. same direction asthexsznd tion with a line circuit having duplex terminal circuits associated therewith, of a sec ondli'ne circuit alsohaving: duplexterminal circuits associated therewith, each of said terminal circuits having a transmittim:

duplex set and an inductivecoupling between the said tl'tlDSl-llltillllgbltlnGl]GSOfii'llO terminal circuits at the sameends-o .a lliiof the said'circuits so arranged that the trans mission of signaling currentthroughtthe windingof the said coupling connectedwith the tern'iinal circuit ofgone linetwillin cluce a current 1 in I the" direction opposite to the signaling current of "the first line in. the winding connected with the corresponding terminal circuit of the said other line circuit.

6. In a system for reducing receiving-end cross-fire in telegraph circuits, the combination with a line circuit having duplex terminal circuits associated therewith, of a second line circuit also having duplex terminal circuits associated therewith, each of said terminal circuits having a transmitting branch connected with the apex thereof, means for coupling together the transmitting branches of the said terminal circuits at the same end of all of said circuits, the said coupling being so arranged that the transmission of signaling current through one of said transmitting branches Will produce a neutralizing current in the trans mitting branches coupled therewith, the direction of which will be opposite to that of the signaling current, the said neutralizing current being applied to the other circuits in a manner adapted to neutralize the interfering currents in the receiving apparatus at the distant ends thereof without affecting the receiving relay connected with the said Other terminal circuits at the same end of the line circuits where the neutralizing impulse is applied.

7. In a system for reducing receiving-end cross-fire in telegraph circuits, the combination with aplurality of line circuits of a plurality of duplex terminal circuits individual to and connected with the opposite ends thereof, each terminal circuit having a transmitting branch connected with the apex of the said terminal circuit for applying signaling impulses for transmission over the said line circuit, and an inductive coupling device comprising a plurality of windings individual to and connected with the said transmitting branches, the said windings be ing so arranged that the flow of signaling current through one of the said windings will create a flow in opposite direction in the other of said windings.

8. In a system for reducing receiving-end cross-fire in telegraph circuits, the combination with a. plurality of line circuits, of duplex terminal circuits individual to and connected with each end of said line circuits, the said terminal circuits comprising a line branch, an artificial line branch, and a transniitting branch connected with the junction of the said other branches, and a transformer having a plurality of windings individual to and connected with the transmitting branches of the terminal circuits in order to inductively connect the said line circuits and to minimize receiving-end cross-lire.

9. In a system for reducing receiving-end cross-fire in telegraph circuits, the combination with a plurality of line circuits of du plex terminal circuits connected with the ends of the said line circuits, the said terminal circuits comprising a line branch, an artificial line branch, and a transmitting branch connected with the junction of the said other branches, and a transformer having a plurality of windings individual to and connected with the transmitting branches of the correspondingly located terminal circuits, the windings being so disposed that the transmission of a signaling impulse through one of the said windings will create an impulse in opposite direction in the others.

10. In a system for reducing receiving-end cross-fire in telegraph circuits, the combination with a plurality of line circuits oft duplex terminal circuits individual to and 0011- nected with the said line circuits, each of said terminal circuits comprising a line branch, an artificial line branch and a transmitting branch connected with the junction of the said other branches, a transformer having a plurality of windings individual to and connected with the transmitting branches oi? the said duplex terminal circuits adapted to inductively connect all of the transmitting branches corresponding gly located, and means to control the magnitude, wave shape, and phase relations 0i currents flowing through the said line circuits.

In testimony whereof, I have signed my name to this specification this 30th day oi January 1922.

SAMUEL I. coni 

